The check engine light came on in my corolla a week ago. I checked some stuff and noticed the oil and exhaust smelled like gas and gas mileage was down 4 mpg. The air filter was very dirty, so I replaced the air filter, made sure the gas cap was tight and had my friend check the check engine light and clear it. The code was P0171: system too lean bank 1. The check engine light just came back on. The symptoms make me think the fuel mixture is too rich, which I would think is because of a bad oxygen sensor. If so, is the oxygen sensor the only problem here, and where is the bank 1 sensor?
Nov 18, 2015 at 8:45 PM
